AM335x CPSW reset (was "RE: [PATCH 04/11] ARM: OMAP2+: usb_host_fs: add custom reset for usb_host_fs (fsusb)")

[Paul Walmsley <paul@xxxxxxxxx>]

Hi

On Fri, 8 Jun 2012, Hiremath, Vaibhav wrote:

> In case of AM33xx, recently I came across similar issue (rather more 
> than this) with CPSW module.
> 
> The issue is,
> 
> We have observed that, in order to disable the CPSW module 
> (MODULEMODE=0x0), We have to assert OCP level reset, before disabling 
> it; else module enters into unknown state, where register status shows, 
> MODULEMODE turns 0x0, but idlests says module is busy.
> 
> This has to be done everytime you try to disable the module.
> 
> The worst part here is, CPSW has 4 submodules (SS, SL1, SL2, CPDMA),
> We have to assert reset signal to each submodules.
> 
> So the approach I had taken is, I had implemented almost similar 
> function specific to cpsw and introduced flag called 
> HWMOD_SWSUP_RESET_BEFORE_IDLE.

Why "SWSUP" ? 

> Now the question here would be, should we consider this IP bug or 
> integration bug? If it is integration bug, then isn't this device issue?

I don't know if it's a bug in either place, but it sounds like something 
that needs to be handled in the _am335x_disable_module() code in 
mach-omap2/omap_hwmod.c.


- Paul
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